Nano coatings take off
A nanoparticle coating for aircraft engines that could triple service life has been developed at University West, in Sweden. The coating uses nanoparticles in the insulating surface layer that protects the engine from heat.
Nicholas Curry, Materials Engineer at University West explains, ‘We have developed a suspension plasma sprayed (SPS) coating. A nano-scale powder is suspended in a liquid carrier, such as ethanol, to allow the powder to be transported into the plasma jet. We used yttria-stabilised zirconia, but the technique is suitable for many other ceramics, and possibly metals too. The coating’s properties are attained by the structure generated in this deposition process, rather than the materials themselves.’
The next phase of research will look to control the structure of the surface layer in order to increase its insulating properties. Curry says, ‘This coating is able to generate columnar structures that were impossible with the conventional powder method. Such coatings have the ability to replace electron beam physical vapour deposition coatings that are used on turbine blades and vanes and engines.’ The main advantage of this novel coating is lower costs – both in terms of investment and production. ‘It potentially opens up the market to more suppliers and to new components that could not be coated previously due to cost or access limitations,’ Curry says.
The process could also be used in other applications, using different materials. Curry suggests, ‘Coatings produced by the SPS method are not limited to thermal barrier coatings. There is potential for the technique to be used for hard, wear-resistant, bio-compatible coatings, electronics, self-cleaning surfaces and catalytic surfaces. We are still thinking of new applications for it.’
The team hopes to see the coatings used in aircraft engines in the near future. Curry says, ‘The production-ready equipment is available and so is the feedstock material. So the technique is ready for application. At the moment, the first use on an aircraft depends on how quickly it is tested and certified by the engine manufacturers. We hope that it will be ready within the next two years.’